Field of the Invention
This invention pertains to treatment of disease and biological conditions mediated at least in part by one or more galectins. Galectins are a family of lectins (sugar binding proteins) that are characterized by having at least one carbohydrate recognition domain (CRD) with an affinity for beta-galactosides. These proteins were recognized as a family only recently, but are found throughout the animal kingdom, and are found in mammals, birds, amphibians, fish, sponges, nematodes and even fungi. This application focuses on galectins in mammals, and in particular, humans. Although the invention herein may be employed with both companion animals (e.g., pets such as dogs and cats) and commercial animals (such as cows, pigs and sheep) the methods and subject matter addressed herein are particularly focused on the treatment of humans.
Galectins mediate and modulate a wide variety of intracellular and extracellular functions, and thus are both expressed within the cell and frequently targeted to a specific cytosolic site, and secreted from the cell, for distribution extra-cellularly, as a component of human plasma. Among the many functions that are mediated by extracellular galectins are inflammation, fibrosis formation, cell adhesion, cell proliferation, metastatic formation, angiogenesis (cancer) and immunosuppression.
Galectins are a family of fifteen (15) carbohydrate-binding proteins (lectins) highly conserved throughout animal species. Most galectins are widely distributed, though galectin-5, -10 and -12 show tissue-specific distribution. While galectins are variably expressed by all immune cells, they are upregulated in activated B and T cells, inflammatory macrophages, natural killer (NK) cells, and FoxP3 regulatory T cells. Galectins contain a variety of structural arrangements, but a relatively conserved carbohydrate recognition domain (CRD). The majority of galectins display a single CRD, and are biologically active as monomers (galectin-5, -7 and -10), or require homodimerization for functional activity (galectin-1, -2, -11, -13, -14 and -15). Alternatively, tandem-repeat-type galectins (galectin-4, -8, -9, and -12) contain two CRDs separated by a short linker peptide, while galectin-3 (chimeric type) has a single CRD fused to a non-lectin domain that can be complexed with other galectin-3 monomers to form an oligomeric pentamer. Of note, some galectins, such as galectin-10, bind to mannose-containing glycans. Among the family of galectins, -1, -3, and -9 are particularly important as potential therapeutic targets, and -2, -4, -5, -6, -7, -8, -10, -11, -12, -13, -14, and -15 also appear implicated in a variety of biological pathways associated with morbidity and mortality.
Thus, galectin-7 has been implicated in the development of certain forms of cancer. St. Pierre et al, Front. Biosci., 1:17, 438-50 (2012) and in a variety of specific cancers, including gal-2, -4 and -8 in the context of colon and breast cancer, Barrow et al, Clin. Cancer Res., 15; 17 (22) 7035-46 (2011). Squamous cell carcinoma of the tongue, Alves et al., Pathol. Res. Pract. 15; 207 (4) 236-40 (2011) has been shown to be associated with elevated levels of gal-1, -3 and -7, while cervical squamous carcinoma has been shown linked to gal-7 levels, Zhu et al, Int. J. Cancer, (August, 2012). A number of galectins, including gal-15, gal-13 and gal-10 have been demonstrated to be linked to implantation and pregnancy concerns. See, e.g., Than et al, Eur. J. Biochem. 271 (6) 1065-78 (2004), Lewis et al, Biol. Reprod. 77 (6); 1027-36 (2007). A number of galectins, including gal-2, 3, 8 and others have been identified as correlating with various autoimmune disorders, such as lupus. Salwati et al, J. Infect. Dis. 1; 202 (1) 117-24 (2010), Pal et al, Biochim. Biophys. Acta., 1820 (10) 1512-18 (2012) and Janko et al, Lupus 21 (7):781-3 (2012). Elevated levels of a number of galectins, including gal-3, are associated with inflammation and fibroses encountered in wound healing and the like. Gal et al, Acta. Histochem. Cytochem. 26:44 (5); 191-9 (2011).
Quite obviously, mediation of inflammatory and fibrotic pathways makes galectins critical elements of a wide variety of disease, injury and trauma related phenomena. In many cases, the presence of unwanted concentrations of galectins can aggravate a disease condition or trauma situation, or interfere with attempts to treat diseases, such as cancer or congestive heart failure. Among the family of galectins recognized as active in humans, galectin-1, galectin-3 and galectin-9 are of particular interest. As indicated above, these proteins are generally referred to, and referred to herein as, gal-1, gal-3 and gal-9. A wide variety of conditions in humans, ranging from problems in conceiving to asthma to chronic heart failure to cancer to viral infection to stroke and beyond are mediated or aggravated by higher than normal concentrations of galectins. Thus, among other galectins, gal-3 is particularly prominent in fibrosis, inflammation and cell proliferation, while gal-1 also plays a role in the immunosuppression required for a successful pregnancy. Gal-1 is also thought to be involved in the differentiation of nerve cells. Gal-9 has been shown to be involved in the control of lesions arising from immunoinflammatory diseases, and is generally implicated in inflammation—gal-9 apparently plays a role in eosinophil recruitment in inflammatory sites. It also appears to mediate apoptosis in certain activated cells.
While the discussion herein is applicable to circulating active gal-1, gal-3 and gal-9, and galectins in general, where elevated circulating galectin levels are associated with disease or injury conditions, more has been elucidated about the role of gal-3 in disease and trauma progression than any of the other galectins, and so it is exemplified herein. More specifically, this invention focuses on the removal of active gal-3 from mammalian, particularly human, plasma. Gal-3 has been shown to be involved in a large number of biological processes, many of which are related to disease states of various kinds. Binding and blocking activity of gal-3 in the circulation, or removal of large amounts of gal-3 from circulation may therefore improve existing medical treatments, suppress and/or reduce inflammation and fibrosis resulting from others, and make it possible to intervene in various disease states not otherwise easily treated. The invention is equally applicable to the reduction in circulating levels of other active galectins to address conditions mediated by those galectins. By “active” galectins, what is referred to is biologically active molecules. As noted, for example, gal-3 can be active, that is, mediate mammalian responses to various traumas and conditions, as a monomer and as an oligomer. In any mammal, at any given time, significant amounts of gal-3 and other galectins are present in an inactive state—that is, they are either tissue bound or ligand bound in such fashion as to inhibit molecular interaction. While such galectins molecules may become active, and may be or become the target of removal by the invention disclosed herein, when monitoring patient conditions and controlling responses, the focus of the invention is the removal of active galectins from the blood stream. This invention makes use of plasmapheresis, sometimes referred to as therapeutic plasma exchange, to control levels of gal-3, and more specifically biologically active galectin, in circulation. Plasma is lead through a fluid pathway and either intermixed with a gal-3 binding agent which can be separated from the plasma, or returned to the body with blocked inactivated gal-3, or lead past a solid support which binds gal-3, the plasma being subsequently returned to the body with a reduced level of gal-3. Thus, this invention can be used to remove bound gal-3 as part of a strategy to reduce total gal-3 content. The focus, in this application, however, is to remove active or unbound gal-3 as a therapeutic measure.
Related Art
This application is related to U.S. patent application Ser. No. 13/153,648, filed Jun. 6, 2011. That application in turn claims priority benefit to U.S. patent application Ser. No. 11/485,955, filed Jul. 6, 2006. The content of both these patent applications is expressly incorporated herein-by-reference. In U.S. patent application Ser. No. 13/153,648 (U.S. Patent Publication US-2011-0294755 A1) a method of treating cell proliferation conditions, inflammation and aggravated fibroses is disclosed which involves the administration of an agent that can bind circulating gal-3, such as modified citrus pectin, (MCP), a citrus pectin which has a reduced molecular weight of twenty thousand (20,000) Daltons or less, preferably ten thousand (10,000) Daltons or so. MCP is available commercially from EcoNugenics of Santa Rosa, Calif. and is discussed in U.S. Pat. Nos. 6,274,566 and 6,462,029.